Second babies - forgetting for a moment about unsuccessful pregnancies -apparently take up more room. I know, I know, that band of muscles in my middle never did shape back up, but still.
Check me out at 33 weeks pregnant, taken in a mirror in Madrid, just one week before giving birth to P. Compare that to yours truly right now at a mere 20 weeks pregnant. I anticipate that in a month or two strangers will be saying things like "You must be ready to pop!" and I'll have to smile blandly and reply "No, I have ages to go, really."
I also weigh more now than I did immediately before P. was born, but I'm trying not to think about that since it's just a plain silly thing to fixate on. Not to mention that I don't want to inadvertently teach P. to think about her own weight by making mine an issue.